Numerical Simulations of Convective Boundary Layers under Different Stability Categories of the Pasquill–Gifford Chart

Numerical simulations of convective boundary layers (CBLs) based on the stability categories of the Pasquill–Gifford (PG) chart were conducted using a large-eddy simulation (LES) model. We studied the simulation settings for different combinations of wind speeds and sensible heat fluxes that could quantitatively generate turbulences satisfying the requirement of each stability category. Additionally, we determined appropriate CBL depths for desired turbulence generation and verified the effectiveness of the velocity scale (w^*) in turbulence generation simulations. This study identified wind speed and sensible heat flux combinations that could generate turbulences under the atmospheric stability categories B (unstable), C (weakly unstable), and D (neutral). However, the results did not follow the scaling law based on w^* in category D when the CBL depth was 600 m. A shallower CBL (300 m depth) should be set in category D to generate turbulence under the scaling law based on w^*. In category B, the transient layer disappeared due to active thermals in the CBL when the depth was 300 m. These results indicated that we should set appropriate CBL depths in addition to horizontal wind speeds and sensible heat fluxes to generate desired and scalable turbulences based on the PG chart.